The present invention relates to a cooking appliance having an automatic power off function which automatically switches off a heater a predetermined period after a last operation.
Prior cooking appliances which use plural halogen lamps as a heater have an automatic power off function. The cooking appliance comprises a rectangular box-shaped outer case and a heat resistant glass plate fixed on a top of the outer case. The halogen unit, which is positioned within the outer case and under the glass plate, heats a pan and the like which is placed on the glass plate. The operator can turn on and off the halogen unit and adjust the power of the halogen unit by operating keys of an operation panel. The automatic power off function automatically turns off the halogen unit when the halogen unit is on for a predetermined time, for instance one hour, during which the operator does not operate the key.
As a result, even if the operator forgets to turn off the halogen unit, the unit is safe and does not waste energy because the halogen unit is automatically turned off in the certain time. When the halogen unit is automatically turned off, the cooking appliance informs the operator that it has been turned off by sounding a buzzer for a short period.
The cooking appliance works for plural kinds of cooking, for example, a short term cooking and a long term cooking such as a stew which takes more than one hour. When the operator cooks the stew requiring a longer time than the automatic power off function, the operator must operate the key before the certain period elapses or turn on the halogen unit again after the halogen unit is turned off.
However, the buzzer rings such a short time that the operator might fail to hear the buzzer and unaware that the halogen unit had been turned off. Therefore, the cooking of the stew is interrupted in the midst of its cooking. Also, since it is difficult for the operator to recognize that the halogen unit is turned off by the automatic power off function, the operator might misrecognize it as a breakdown or a malfunction.